Lint to detect dangling identifiers in docs (#240).

lib/src/rules.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library linter.src.rules;
 
 import 'dart:collection';
 
 import 'package:linter/src/config.dart';
 import 'package:linter/src/linter.dart';
 import 'package:linter/src/rules/always_declare_return_types.dart';
 import 'package:linter/src/rules/always_specify_types.dart';
 import 'package:linter/src/rules/annotate_overrides.dart';
 import 'package:linter/src/rules/avoid_as.dart';
 import 'package:linter/src/rules/avoid_empty_else.dart';
 import 'package:linter/src/rules/avoid_init_to_null.dart';
 import 'package:linter/src/rules/avoid_return_types_on_setters.dart';
 import 'package:linter/src/rules/await_only_futures.dart';
 import 'package:linter/src/rules/camel_case_types.dart';
+import 'package:linter/src/rules/comment_references.dart';
 import 'package:linter/src/rules/constant_identifier_names.dart';
 import 'package:linter/src/rules/control_flow_in_finally.dart';
 import 'package:linter/src/rules/empty_constructor_bodies.dart';
 import 'package:linter/src/rules/hash_and_equals.dart';
 import 'package:linter/src/rules/implementation_imports.dart';
 import 'package:linter/src/rules/library_names.dart';
 import 'package:linter/src/rules/library_prefixes.dart';
 import 'package:linter/src/rules/non_constant_identifier_names.dart';
 import 'package:linter/src/rules/one_member_abstracts.dart';
 import 'package:linter/src/rules/overriden_field.dart';
@@ skipping 17 matching lines @@
 final Registry ruleRegistry = new Registry()
   ..register(new AlwaysDeclareReturnTypes())
   ..register(new AlwaysSpecifyTypes())
   ..register(new AnnotateOverrides())
   ..register(new AvoidAs())
   ..register(new AvoidEmptyElse())
   ..register(new AvoidReturnTypesOnSetters())
   ..register(new AvoidInitToNull())
   ..register(new AwaitOnlyFutures())
   ..register(new CamelCaseTypes())
+  ..register(new CommentReferences())
   ..register(new ConstantIdentifierNames())
   ..register(new UnrelatedTypeEqualityChecks())
   ..register(new EmptyConstructorBodies())
   ..register(new TestTypesInEquals())
   ..register(new OverridenField())
   ..register(new HashAndEquals())
   ..register(new ImplementationImports())
   ..register(new LibraryNames())
   ..register(new LibraryPrefixes())
   ..register(new NonConstantIdentifierNames())
@@ skipping 35 matching lines @@
   /// enables `my_rule`.
   ///
   /// Unspecified rules are treated as disabled by default.
   Iterable<LintRule> enabled(LintConfig config) => rules
       .where((rule) => config.ruleConfigs.any((rc) => rc.enables(rule.name)));
 
   void register(LintRule rule) {
     _ruleMap[rule.name] = rule;
   }
 }